Compositions for the Removal of Silicone Deposits

ABSTRACT

A solvent composition has an oxygenated solvent and a siloxane solvent. In one embodiment, the oxygenated solvent is propylene glycol methyl ether and the siloxane solvent is hexamethyldisiloxane or octamethyltrisiloxane. In another embodiment, the solvent composition is an azeotrope of propylene glycol n-butyl ether and decamethyltetrasiloxane. The siloxane solvent can be used in any situation where one desires to remove a silicone deposit, e.g., conformal coatings, adhesives, sealants, greases, heat transfer fluids, paints, oils, etc.

CLAIM OF DOMESTIC PRIORITY

The present application is a continuation of U.S. patent applicationSer. No. 16/704,208, filed Dec. 5, 2019, which claims the benefit ofU.S. Provisional Application No. 62/852,950, filed May 24, 2019, whichapplication are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to compositions for the removal of curedor uncured silicone deposits, methods of making, and methods of usingthe compositions.

BACKGROUND OF THE INVENTION

Silicone is commonly used in a wide variety of fields. Silicone is usedto provide electrical insulation, as a protective coating overelectronics, as a sealant in household, automotive, or aerospace uses,and in innumerable other situations. Silicone comes into play in almostevery conceivable industry.

Silicone-containing fluids can be reactive or non-reactive dependingupon the formulation and desired end use. These fluids are selected foruse due to their versatility, durability, and water and chemicalresistance. Forms associated with reactive and non-reactive siliconefluids range from uncured oils, greases, and heat transfer fluids, tocured sealants, adhesives, paints, and conformal coatings. Allsilicone-containing fluids are notoriously difficult to clean or removefrom industrial and surface mount technology surfaces without damagingthe substrates, or without requiring high temperatures and specializedequipment.

Uncured silicone fluids typically require cleaning solution temperaturesabove the silicone fluid softening point, which is often unattainable intypical cleaning applications. Cured silicone fluids typically require adigestant in aqueous media to break the polymeric silanol network, andthese common digestants are potentially damaging to the substrate towhich they are attached since silanol bonds of cured silicone fluids areformed with the active substrate as well.

Siloxane solvents have been used to remove silicone deposits, becausesiloxane reacts with silicone. However, using siloxane solvents involvesat least two major drawbacks. First, siloxane solvents are prohibitivelyexpensive for most use-cases. Second, a lot of silicone adhesives,coatings, greases, etc., include other ingredients besides purelysilicone. The additives reduce the effectiveness of the siloxanesolvents.

Therefore, a need exists for improved solvent compositions for removalof silicone deposits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1b illustrate mixing a plurality of solvents to form a newsolvent composition; and

FIGS. 2a-2h illustrate removing a conformal silicone coating from a PCBusing the new solvent composition.

DETAILED DESCRIPTION

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Combining a volatile siloxane solvent with an oxygenated solvent in thediol or glycol ether class creates a broad-spectrum silicone depositremoval solution that acts on a wide variety of both cured and uncuredsilicone fluids or deposits, does not require extreme temperatures toreach the silicone fluid softening points, and can interrupt thepolymeric silanol network of cured silicone fluids without damagingsubstrate material.

The oxygenated solvent is selected from the following non-exhaustivelist in some embodiments: ethylene glycol, diethylene glycol,triethylene glycol, propylene glycol, dipropylene glycol, tripropyleneglycol, butylene glycol, dibutylene glycol, tributylene glycol,pentylene glycol, dipentylene glycol, tripentylene glycol, hexyleneglycol, dihexylene glycol, trihexylene glycol, heptylene glycol,diheptylene glycol, triheptylene glycol, octylene glycol, dioctyleneglycol, trioctylene glycol, propylene glycol methyl ether, dipropyleneglycol methyl ether, tripropylene glycol methyl ether, propylene glycolmethyl ether acetate, dipropylene glycol methyl ether acetate, propyleneglycol n-propyl ether, dipropylene glycol n-propyl ether, propyleneglycol n-butyl ether, dipropylene glycol n-butyl ether, tripropyleneglycol n-butyl ether, propylene glycol phenyl ether, propylene glycoldiacetate, dipropylene glycol dimethyl ether, diethylene glycol ethylether, diethylene glycol methyl ether, diethylene glycol n-butyl ether,diethylene glycol hexyl ether, diethylene glycol n-butyl ether acetate,ethylene glycol propyl ether, ethylene glycol n-butyl ether, ethyleneglycol hexyl ether, ethylene glycol n-butyl ether acetate, triethyleneglycol methyl ether, triethylene glycol ethyl ether, triethylene glycoln-butyl ether, ethylene glycol phenyl ether, and ethylene glycol n-butylether.

The siloxane solvent is selected from the following non-exhaustive listin some embodiments: hexamethyldisiloxane, octamethyltrisiloxane,decamethyltetrasiloxane, dodecamethylpentasiloxane,polydimethylsiloxane, phenylmethylsiloxane, dimethyl-diphenylsiloxane,cyclomethicone, octamethylcyclotetrasiloxane,decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, andpolymethylhydrogensiloxane.

To create the new solvent composition, any of the desired solvents aremixed together, with at least one oxygenated solvent and one siloxanesolvent in the mixture. FIGS. 1a and 1b illustrates mixing two solventstwo create a new solvent composition 100. An oxygenated solvent 110 anda siloxane solvent 112 are each poured into a beaker or other container120 in FIG. 1 a. Any suitable container for mixing solvents can be usedinstead of beaker 120, e.g., a vat, a bucket, a bottle, a barrel ordrum, etc. Oxygenated solvent 110 and siloxane solvent 112 can be pouredfrom beakers, bottles, or another suitable container as illustrated,from a machine with a fluid conduit and nozzle, or via any othersuitable fluid dispensing mechanism. Oxygenated solvent 110 and siloxanesolvent 112 can be dispensed simultaneously or one after the other witheither solvent added to the other.

Oxygenated solvent 110 and siloxane solvent 112 will typically be ableto thoroughly mix simply by adding the two solvents into a containertogether. However, in some cases the solvents may need to be agitated tofully mix into solvent composition 100. FIG. 1B illustrates agitatingusing a mixing rod 130. Mixing rod 130 is inserted into beaker 120 andmoved around to cause oxygenated solvent 110 and siloxane solvent 112 tomix together into solvent composition 100. The solvents can be agitatedby inserting any suitable mixing device into beaker 120, e.g., a spoon,spatula, or paint mixer. In some embodiments, a motor is attached to themixing device to automatically agitate the solvents. The solvents canalso be mixed by agitating beaker 120 while both solvents are containedin the beaker, e.g., by placing the beaker on a moving platform or bypicking up and moving the beaker around.

Solvent composition 100 is shown as a binary solvent, with twoconstituent solvents. However, solvent composition 100 can also beformed as a ternary solvent with three constituent solvents, aquaternary solvent with four constituent solvents, or even more solventscould be combined. The key is that at least one oxygenated solvent andone siloxane solvent is used. Binary solvents operate better in somesituations than mixing a higher number of solvents because the smallersolvent molecules in a binary solvent will get into the microscopicpores of the silicone material easier. Steric hinderance can become aproblem with some ternary or quaternary solvents for some uses. However,having the additional qualities of more solvents in solvent composition100 may be preferable in other use-cases.

One consideration for selecting the specific solvents to combine isboiling point, evaporation rate, or vapor pressure. For most use-cases,a faster evaporating solvent is desirable so that the solvent evaporatesoff of the substrate quicker. Therefore, constituent solvents with afaster evaporation rate, lower vapor pressure, or lower boiling pointcan be selected to reduce the amount of time the solvent composition 100remains on the substrate after application.

Of the above-listed solvents, propylene glycol methyl ether is thefastest evaporating oxygenated solvent, and hexamethyldisiloxane is thefastest evaporating siloxane solvent. Therefore, a mixture withpropylene glycol methyl ether as oxygenated solvent 110 andhexamethyldisiloxane as siloxane solvent 112 makes a suitable solventcomposition 100 with a relatively fast evaporation rate.Octamethyltrisiloxane is the second fastest evaporating siloxane solventof the above-listed solvents. A mixture of propylene glycol methyl etheras oxygenated solvent 110 and octamethyltrisiloxane as siloxane solvent112 would also make a suitable solvent composition 100 with a relativelyfast evaporation rate.

Oxygenated solvent 110 and siloxane solvent 112 can be mixed in anyratio. Siloxane solvent 112 is generally more expensive than oxygenatedsolvent 110. Therefore, a lower percentage of siloxane solvent 112 willgenerally reduce the overall cost of solvent composition 100. However,lowering the percentage of siloxane solvent 112 below a lower thresholdwill undesirably reduce the effectiveness of solvent composition 100 atdissolving silicone. Reducing the percentage of siloxane solvent 112below about 15% by weight has been found to affect the ability ofsolvent composition 100 to dissolve silicone, while keeping thepercentage at or above 15% has not had a significant impact on thecapabilities of the solvent composition. Therefore, in one embodiment,solvent composition 100 is formed with 15% by weight or greater ofsiloxane solvent 112.

In some cases, a particular oxygenated solvent 110 matched with aparticular siloxane solvent 112 forms an azeotrope. An azeotrope is amixture of two or more liquids whose proportions cannot be altered orchanged by simple distillation. This happens because when an azeotropeis boiled, the resultant vapor has the same proportions of constituentsas the unboiled mixture. To form an azeotrope, a certain percentage ofeach constituent solvent is required depending on the particularsolvents selected. For some combinations of particular oxygenatedsolvents 110 and siloxane solvents 112, an azeotrope is not possible.For other solvents, the azeotrope may have undesirable properties, suchas a slower evaporation rate than the constituents or requiring apercentage of siloxane solvent 112 that is too low for the solventcomposition 100 to be effective.

One particular effective azeotrope is a mixture using propylene glycoln-butyl ether for oxygenated solvent 110 and decamethyltetrasiloxane forsiloxane solvent 112. An azeotrope is formed when mixed in the ratio of15% decamethyltetrasiloxane to 85% propylene glycol n-butyl ether byweight. While neither of the individual solvents in the azeotrope arethe fastest evaporating from their respective lists above, the azeotropehas a faster evaporating rate than either of the constituent solvents.The azeotrope formed with 15% decamethyltetrasiloxane and 85% propyleneglycol n-butyl ether has an evaporation rate that is on par with anyother known combination.

Once solvent composition 100 has been mixed using any of the abovedescribed combinations, the solvent composition can be used in anysituation where one desires a silicone deposit be removed. FIGS. 2a-2hillustrate one situation in which solvent composition 100 isparticularly useful. FIG. 2a shows an exemplary printed circuit board(PCB) 200. PCB 200 can have any combination of electrical componentsmounted onto the PCB. PCB 200 can be a stand-alone electrical systemthat uses the semiconductor packages to perform one or more electricalfunctions, such as an HVAC controller or a vehicle electronic controlunit. Alternatively, PCB 200 can be a subcomponent of a larger system.For example, PCB 200 can be part of a tablet computer, cellular phone,digital camera, communication system, or other electronic device. PCB200 can also be a graphics card, network interface card, or anothersignal processing card that is inserted into a computer.

In FIG. 2a , a variety of semiconductor packages 210 and surface mountcomponents 212 are mounted onto PCB 200 to form an electrical system. Ingeneral, any suitable component can be used, such as semiconductorpackages with integrated circuits or discrete active or passive partssuch as diodes, transistors, inductors, or capacitors. Semiconductorpackages 210 can include microprocessors, memories, ASICs, logiccircuits, analog circuits, RF circuits, or other semiconductor die orelectrical components. Any other desired electrical component can beused as needed for a desired electrical functionality to be performed byPCB 200.

In FIG. 2a , PCB 200 has been completely assembled and is functionallycomplete. FIG. 2b shows a conformal silicone coating 220 being appliedby a spray applicator with nozzle 222. Nozzle 222 releases a mist 224 ofsilicone material that forms conformal silicone coating 220. Applyingconformal silicone coating 220 is a common finishing step to protect acompleted PCB from water and other contaminates when deployed.

FIG. 2c shows a cross-section of PCB 200 with one of the surface mountcomponents 212 covered in silicone coating 220. One reason that siliconecoating 220 may be removed is to replace or upgrade one of the parts.For example, component 212 might be a resistor that has blown out andcreated an open circuit. A semiconductor package 210 may be replaced toupgrade microcontroller capabilities or memory size. Rather thancompletely replace PCB 200, components 210 and 212 can be replaced torepair or upgrade the PCB. However, replacing a component is difficultwithout first removing coating 220 over the component.

Solvent composition 100 allows removal of coating 220. First, solventcomposition 100 is applied onto coating 220. FIG. 2d shows one simplemethod of applying solvent composition 100 to a small localized areausing dropper 230. With dropper 230, coating 220 can be removed over asingle component 210 or 212, or a small grouping of components, withoutremoving the coating over the rest of PCB 200.

Solvent composition 100 is deposited onto coating 220 over component 212in FIG. 2d and immediately begins to dissolve the coating. The siloxanesolvent 112 in the mixture attacks the silicone. Oxygenated solvent 110not only reduces the cost of solvent composition 100, but also improvesthe dissolving action. When coating 220 is applied, there are usuallycuring agents mixed in with the silicone. The curing agents absorb waterto harden coating 220, which forms a silanol network within the coating.The silanol network provides a relatively high attraction of coating 220to PCB 200 but is not dissolved by siloxane solvent 112. Oxygenatedsolvent 110 in solvent composition 100 destroys the silanol network incoating 220, resulting in a much faster dissolving of the coating thanhaving only siloxane solvent 112 to dissolve the silicone portion.Oxygenated solvent 110 also helps remove other impurities such as waterand other polarized molecules or flux left over from the manufactureprocess. Solvent composition 100 can also be used to remove flux duringmanufacture of electronic devices prior to deposition of coating 220.

Solvent composition 100 can be applied using any other suitable method.FIGS. 2e and 2f illustrate two other non-limiting methods forapplication. In FIG. 2e , solvent composition 100 is disposed in anaerosol spray can 232 and sprayed onto PCB 200. Aerosol can 232 allowsapplication of solvent composition 100 over a larger area of PCB 200than with dropper 230 while still allowing localized application. A useraims the spray stream from aerosol can 232 at a particular component orgroup of components to remove coating 220 over those componentspecifically. Alternatively, aerosol can 232 can be used to applysolvent composition 100 over an entire surface of PCB 200.

In one embodiment, aerosol can 232 is used to apply solvent composition100 over an area of PCB 200, and then the solvent composition is allowedto set on top of coating 220 to dissolve the coating. In anotherembodiment, aerosol can 232 is used to apply a constant spray of solventcomposition 100 onto an area of PCB 200. The continuing spray of solventcomposition 100 actively dissolves and washes away coating 220 while thestream flows over PCB 200. Aerosol can 232 can be held at a low anglerelative to PCB 200 to spray solvent composition 100 under componentsand in other tight areas on the PCB, which helps to fully remove coating220.

For some configurations of solvent composition 100, the ratio ofsiloxane solvent 112 to oxygenated solvent 110 will need to be increasedto provide an adequate stream of the solvent composition from theaerosol nozzle. For a typical aerosol can 232, the mixture of solventcomposition 100 may need to be at least 50% by weight of siloxanesolvent 112 to create an adequate stream of the solvent composition. Thestream could also potentially be improved by modifying aerosol can 232or by picking different constituent solvents.

In FIG. 2f , PCB 200 is disposed into a bath 234 of solvent composition100. Bath 234 is a container filled with solvent composition 100sufficiently to fully cover PCB 200. PCB 200 soaks in bath 234 whilesolvent composition 100 dissolves coating 220. In some embodiments, apump is used to create a flow of solvent composition 100 over PCB 200.

In FIG. 2g , a brush or other tool 236 is used to supplement thedissolving action of solvent composition 100. Solvent composition 100 isfirst applied using any suitable application method, including thosediscussed above. After waiting a sufficient time for coating 220 todissolve, typically a few seconds or minutes, brush 236 can be used toscrub off coating 220. The bristles of brush 236 help remove partiallydissolved portions of coating 220 and distribute solvent composition 100to nooks and crannies where a thicker buildup of the coating wasdeposited. In other embodiments, brush 236 is used to apply solventcomposition 100 without first relying on another application method bydipping the brush in 236 in solvent composition 100 or otherwiseapplying the solvent composition to the brush.

FIG. 2h shows component 212 with coating 220 removed over the component.Component 212 can easily be desoldered and replaced with a workingcomponent to repair PCB 200. After component 212 is replaced, coating220 can be reapplied over the component to make sure that PCB 200 isfully protected. Coating 220 can be applied by spraying a silicone fluidover the entire PCB 200 as shown in FIG. 2b , or just the area where thecoating was removed. Coating 220 can also be replaced by brushing anuncured silicone fluid over component 212, or by any other suitablemethod.

Using solvent composition 100, with a mixture of oxygenated solvent 110and siloxane solvent 112, to remove coating 220 reduces cost andproblems of PCB rework. Coating 220 is dissolved faster so solventcomposition 100 can be removed quicker than with purely siloxane solvent112. Having solvent on PCB 200 for less total time reduces thelikelihood of damage to the PCB. The addition of oxygenated solvent 110not only removes coating 220 faster by attacking the silanol networkwithin the coating, but also helps remove other contaminants thatsiloxane solvent 112 alone would not remove.

Solvent composition 100 is usable and provides benefits in any situationwhere a silicone substance needs to be removed. Misting applicatormachines, such as the one shown in FIG. 2b with nozzle 222, commonlyneed to be cleaned. For instance, if a different liquid besides theuncured silicone fluid needs to be sprayed then the existing siliconewithin and on the machine will need to be fully removed. Solventcomposition 100 can be used to clean nozzles, flow lines, holding tanks,and other parts of misting machines. Misting can also create a mess onthe outside of the machine, or on nearby objects, that can be cleanedwith solvent composition 100.

Silicone calking is commonly used in a variety of industries and aroundthe home as a sealant. Silicone calking, which is notoriously difficultto remove cleanly, can be removed with solvent composition 100. Siliconecalking may need to be removed when replacing one of the components thatthe silicone calking contacts, or just to replace the silicone calkingif the seal fails. Solvent composition 100 can also be used to removesilicone-based adhesives, greases, etc. Siloxane solvent 112 breaks downthe silicone while oxygenated solvent 110 dissolves other additivescommonly used.

Silicone heat transfer fluids are commonly used in a wide variety ofindustries but are problematic to remove or clean. Silicone heattransfer fluid can require cleaning because of an inadvertent spill thatcreates a mess. In other cases, a silicone heat transfer fluid isintentionally applied to parts for testing purposes, and then needs tobe cleaned.

Solvent composition 100 is also useful in uranium extraction. Siliconefluids are used to coat beads of material that uranium is to beextracted from. The silicone fluids expand the beads and pick up uranylnitride that is created. Using solvent composition 100 removes thesilicone from the beads effectively and economically.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed:
 1. A method of removing a silicone deposit, comprising:providing a solvent composition including an oxygenated solvent and asiloxane solvent; providing an object including a silicone depositdisposed on the object; and removing the silicone deposit by using thesolvent composition to dissolve the silicone deposit.
 2. The method ofclaim 1, wherein the object includes an electronic device and thesilicone deposit includes a conformal coating disposed over theelectronic device.
 3. The method of claim 2, further including removingonly a portion of the conformal coating.
 4. The method of claim 2,further including applying the solvent composition as an aerosol stream.5. The method of claim 1, wherein the silicone deposit includes uranylnitride.
 6. The method of claim 1, wherein the silicone deposit includesa thermal transfer fluid.
 7. The method of claim 1, wherein the siloxanesolvent includes hexamethyldisiloxane or octamethyltrisiloxane.
 8. Themethod of claim 1, wherein the solvent composition includes at least 15%of the siloxane solvent by weight.
 9. The method of claim 1, wherein theoxygenated solvent includes propylene glycol n-butyl ether and thesiloxane solvent includes decamethyltetrasiloxane.
 10. The method ofclaim 1, wherein the solvent composition is an azeotrope.
 11. The methodof claim 1, further including selecting the siloxane solvent from agroup consisting of hexamethyldisiloxane, octamethyltrisiloxane,decamethyltetrasiloxane, dodecamethylpentasiloxane,polydimethylsiloxane, phenylmethylsiloxane, dimethyl-diphenylsiloxane,cyclomethicone, octamethylcyclotetrasiloxane,decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, andpolymethylhydrogensiloxane.
 12. The method of claim 11, furtherincluding selecting the oxygenated solvent from a group consisting ofethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, tripropylene glycol, butylene glycol,dibutylene glycol, tributylene glycol, pentylene glycol, dipentyleneglycol, tripentylene glycol, hexylene glycol, dihexylene glycol,trihexylene glycol, heptylene glycol, diheptylene glycol, triheptyleneglycol, octylene glycol, dioctylene glycol, and trioctylene glycol. 13.The method of claim 11, further including selecting the oxygenatedsolvent from a group consisting of propylene glycol methyl ether,dipropylene glycol methyl ether, tripropylene glycol methyl ether,propylene glycol methyl ether acetate, dipropylene glycol methyl etheracetate, propylene glycol n-propyl ether, dipropylene glycol n-propylether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether,tripropylene glycol n-butyl ether, propylene glycol phenyl ether,propylene glycol diacetate, dipropylene glycol dimethyl ether,diethylene glycol ethyl ether, diethylene glycol methyl ether,diethylene glycol n-butyl ether, diethylene glycol hexyl ether,diethylene glycol n-butyl ether acetate, ethylene glycol propyl ether,ethylene glycol n-butyl ether, ethylene glycol hexyl ether, ethyleneglycol n-butyl ether acetate, triethylene glycol methyl ether,triethylene glycol ethyl ether, triethylene glycol n-butyl ether,ethylene glycol phenyl ether, and ethylene glycol n-butyl ether.
 14. Amethod of removing a silicone coating, comprising: providing a printedcircuit board (PCB) including a first electrical component mounted tothe PCB and a silicone coating deposited over the PCB and firstelectrical component; providing a solvent composition including anoxygenated solvent and a siloxane solvent; using the solvent compositionto remove a portion of the silicone coating over the first electricalcomponent; and replacing the first electrical component with a secondelectrical component after removing the portion of the silicone coating.15. The method of claim 14, further including applying the solventcomposition as an aerosol stream.
 16. The method of claim 14, furtherincluding applying the solvent composition using a dropper.
 17. Themethod of claim 14, further including scrubbing the portion of thesilicone coating with a brush while the solvent composition is disposedon the portion of the silicone coating.
 18. A method of removing asilicone coating, comprising: providing a printed circuit board (PCB)including a first electrical component mounted to the PCB and a siliconecoating deposited over the PCB and first electrical component; providinga solvent composition including an oxygenated solvent and a siloxanesolvent; using the solvent composition to remove a first portion of thesilicone coating over the first electrical component while a secondportion of the silicone coating remains on the PCB; and replacing thefirst electrical component with a second electrical component afterremoving the portion of the silicone coating.
 19. The method of claim18, further including selecting the siloxane solvent from a groupconsisting of hexamethyldisiloxane, octamethyltrisiloxane,decamethyltetrasiloxane, dodecamethylpentasiloxane,polydimethylsiloxane, phenylmethylsiloxane, dimethyl-diphenylsiloxane,cyclomethicone, octamethylcyclotetrasiloxane,decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, andpolymethylhydrogensiloxane.
 20. The method of claim 19, furtherincluding selecting the oxygenated solvent from a group consisting ofethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, tripropylene glycol, butylene glycol,dibutylene glycol, tributylene glycol, pentylene glycol, dipentyleneglycol, tripentylene glycol, hexylene glycol, dihexylene glycol,trihexylene glycol, heptylene glycol, diheptylene glycol, triheptyleneglycol, octylene glycol, dioctylene glycol, trioctylene glycol,propylene glycol methyl ether, dipropylene glycol methyl ether,tripropylene glycol methyl ether, propylene glycol methyl ether acetate,dipropylene glycol methyl ether acetate, propylene glycol n-propylether, dipropylene glycol n-propyl ether, propylene glycol n-butylether, dipropylene glycol n-butyl ether, tripropylene glycol n-butylether, propylene glycol phenyl ether, propylene glycol diacetate,dipropylene glycol dimethyl ether, diethylene glycol ethyl ether,diethylene glycol methyl ether, diethylene glycol n-butyl ether,diethylene glycol hexyl ether, diethylene glycol n-butyl ether acetate,ethylene glycol propyl ether, ethylene glycol n-butyl ether, ethyleneglycol hexyl ether, ethylene glycol n-butyl ether acetate, triethyleneglycol methyl ether, triethylene glycol ethyl ether, triethylene glycoln-butyl ether, ethylene glycol phenyl ether, and ethylene glycol n-butylether.